An optoelectronic transducer cuff was developed to chronically measure in vivo the muscular activity of the oviduct by monitoring the changes in optical density (OD) at a point on the oviduct. The cuff consisted of one light emitting diode opposed by two photo transistors and their associated lead wires molded into a "C" shape with an epoxy resin. The resulting optoelectronic transducer cuff was surgically implanted and attached to the ampullary region of the oviduct with a cyanoacrylate tissue glue. Lead wires were exteriorized through the flank and connected to the external system electronics. A study was performed on 4 luteal phase ewes to test how changes in the OD at a point on the oviduct were related to oxytocin treatment. Twenty-four hours after implanting the cuff, logarithmic doses of oxygencin were administered via jugular catheter at 5 hr intervals to each ewe. The frequency signal resulting from changes in OD of the oviduct before treatment ranged from 12 to 18 cycles per min. This signal frequency increased and its amplitude decreased within the first minute post oxytocin injection. The mean maximum increase in the signal frequency of the OD changes following injection were 0.8, 3.8, 6.7, 10.7, 20, 55.8, 58 and 71 cycles per minute corresponding to injections of saline, 1/9, 1/3, 1, 3, 9, 27 and 81 USP units oxytocin, respectively. A semi-log plot of the mean maximum change in the signal frequency versus the oxytocin dose administered exhibited a dose response curve. These data strongly support the concept that changes in the OD of the oviduct are in direct relationship with oviduct contractions. BIBLIOGRAPHIC REFERENCES: Noonan, J.J., R.L. Adair, J.A. Ringo and J.J. Reeves. 1976. Optoelectronic measurement of oviduct motility. J. Animal Science (Abstract).